Through terminal block, 281 Series, operating tool This through terminal block (item number 281-994) is designed for quick and simple connections. Strip lengths must be between 9 and 10 mm when connecting conductors to this through terminal block. Whether in industrial or building applications, our rail-mount through terminal blocks are the perfect solution to quickly and securely connect electrical conductors. Depending on the model, you can use them for either typical through-wiring or potential distribution. Featuring conductor terminals along with CAGE CLAMP®, this connector outperforms the competition. Our proven universal connection known as CAGE CLAMP® is the industry standard for connection technology and electrical interconnections. Depending on the type of conductor, this through terminal block is designed for conductor cross sections ranging from 0.08 mm² to 4 mm². An operating tool is used to operate this through rail-mount terminal block.